Logic X Logic X Software Instrument Panning Issue Help!!!

I'm having an issue with panning in Logic X. After working on a stereo instrument track for a while (i.e. Battery 4 , EXS) the track mysteriously pans 80% to the right however there are no apparent changes to the panning dial (it is still dead center). I go into hyper editor and event list and there are no panning changes. I've unplugged my controller and tried to approach it that way but nothing happens. It must be at the instrument level but I have no idea how this is happening. Any ideas? Thanks!

Thanks for the reply Peter. Yes the level discrepancy is visible in both the channel strip and master bus however the pan pot is centered. Regardless of the instrument it happens the same exact way. It's fine upon loading, I can record midi data, etc and then after a few minutes it happens. I've noticed that it only seems to happen with sample-based instruments (EXS, Battery, Kontakt). When using Battery, the master level meter within the instrument is fine however the discrepancy is still evident in channel strip. Maybe something is happening in between?